Production of high bulk fabrics from staple fiber mixtures



May 30, 1961, WELDON BULK vs Z HIGH SHRINKAGE STAPLE IN YARN Ex.I

BULK I 0 IO 20 3O 4O 5O 6O 7O 8O 90 I00 3 OF HIGH SHRINKAGE STAPLE IN YARN ARTH UR J.

INVENTOR WE L DON ATTORNEY United States Patent PRODUCTION OF HIGH BULK FABRICS FROM STAPLE FIBER MIXTURES Arthur J. Weldon, Newark, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed Nov. 30, 1955, Ser. No. 549,990

1 Claim. (CI. 2872) This invention relates to a novel woven fabric. More specifically it is concerned with a novel high bulk, Woven fabric and a process for its preparation.

It is an object of the present invention to provide a novel and useful high bulk, woven fabric.

Another object is to provide a process for the production of a high bulk, woven fabric.

These and other objects will become apparent in the course of the following specification and claims.

In accordance with the present invention a high bulk fabric having excellent cover and surface continuity is provided by weaving a fabric at a relatively low loom construction from a yarn containing at least two component fibers which possess different shrinkage capacities, at least about 10% of the said yarn being a man-made fiber which has the capacity of being shrunk by a differential at least 10% greater than the capacity of said other component fiber which comprises about 20% of the said yarn, and thereafter shrinking the said fiber having the higher shrinkage capacity by a differential at least 10% greater than the fiber of lower shrinkage capacity to produee a shrinkage stable fabric. By a shrinkage stable fabric as used herein is meant a fabric which under normal conditions of wear, use and conventional cleaning possesses dimensional stability.

The invention will be more readily understood by reference to the drawing. e

The figure shows two curves wherein bulk (in cubic centimeters per gram) is plotted as ordinate versus the percentage of fiber in the fabric which has a 20% residual shrinkage as abscissa. The upper curve, referred to hereinafter in Example I, results from measurements made on a series of fabric constructions as described in that example, while the lower curve, referred to hereinafter in Example II, is a plot of observations made on a series of fabric constructions as described in Example II. These curves illustrate the necessity of employing a yarn containing both high and low residual shrinkage fiber in obtaining a high bulk fabric.

By a fabric having high bulk as the term is employed herein, is meant a woven fabric whose bulk, i.e., cubic centimeters per gram, the thickness being observed by the standard British Standards Institute test, is at least about 15% and preferably a least about 25% greater than the bulk of a fabric of the same weight and tightness woven from yarn of 100% low residual shrinkage.

The following examples are cited to illustrate the invention. They are not intended to limit it in any manner. In the bulk determinations reported, thickness of sample is measured according to standard British Standards Institute methods, employing an Ames gauge and a pressure of grams per square centimeter.

I Example I A 2 x 2 twill fabric of 54 ends by 46 picks in the loom is woven from yarn produced from a polymer of acrylonitrile (wherein the polymer is prepared from a mixture of 95% acrylonitrile and 5% methyl acrylate, cf.

5 having a residual shrinkage of about 3%) to a 34/2 ply Y Patented May 30, 1961 United States Patent No. 2,436,926, dated December 20, 1949), the said yarn being spun on the modified cotton .system from 2 /2 inch, 3 denier staple (20% of which staple has a residual shrinkage of 20%, the remainder cotton count, with a Z twist of 20 turns per inch in the singles and an S twist of 14 turns per inch in the ply.

The fabric is then scoured, in a relaxed state in a Prosperity washing machine having a tumbling action for 45 minutes, at 212 F. in water containing a minor amount (10 grams) of alkyl sulfate as a detergent. After rinsing with Water and vacuum extracting, the fabric is dried at 260 F. in a pin tenter, allowing a filling-wise slack of 1 inch under wet width and a 10% warp overfeed to permit relaxation, at a rate of 2 /2 yards per minute.

After light brushing and shearing the fabric is dry pressed on a Palmer steel drum heated under 45 pounds steam pressure and covered with a blanket, the presser being operated to provide maximum pressure and at its slowest speed.

The fabric so prepared is observed to have a bulk of 4.8 cubic centimeters per gram. 0

A control fabric similarly prepared except that the staple from which the yarn is spun is 100% low residual shrinkage (i.e., has a residual shrinkage of no more than about 3%) and which has a loom count of 70 ends by 56 picks (the compensation being made to produce a fabric of comparable weight and tightness) has a bulk of 3.7 cubic centimeters per gram. The fabric of the present invention thus shows an increase in bulk of 30% over a similar fabric of standard construction.

A series of fabrics, woven from yarn containing various percentages of 20% residual shrinkage staple, is prepared following the technique outlines above and employing fiber of the same polymer of acrylonitrile. From bulk measurement data a curve is drawn plotting bulk versus percentage high shrinkage yarn shown as the upper curve in the figure. As will be apparent from the curve, the high loft of the fabrics of the present invention requires the presence of both high and low residual shrinkage fiber in the yarn construction.

7 Example 11 A 2 x 2 twill fabric of 66 ends by 54 picks in the loom is woven from a yarn mixture containing 40% of 2 /2 inch length, 3 denier polyethylene terephthalate staple possessing a 20% residual shrinkage, 35% of a 2 /2 inch length, 3 denier polyethylene terephthalate staple possessing a residual shrinkage of 3%, and 25 of a 2 inch length, 3 denier, commercialuflow residual shrinkage) regenerated cellulose rayon staple,,to a 34/2 ply cotton count twisted in the manner of the yarn of Example I.

The fabric so prepared is finished according .to the technique and conditions as employed in Example I, except that in'the pressing operation the fabric of this example is 'semidecated, being steamed for 5 minutes with saturated steam at 212 F. and then vacuum dried for 3 minutes to remove moisture. T

The fabric, prepared as described, is observed to have a bulk of 3.3 cubic centimeters per gram.

-A control fabric is prepared employing a yarn spun from a mixture of of 2 /2 inch length, 3 denier polyethylene terephthalate staple having a residual shrinkage of 3% and 25 of 2 inch length, 3 denier commercial regenerated cellulose rayon; The fabric is woven 74 ends by 60 picks in the loom to compensate for weight and tightness to make the samples'truly comparative. The bulk of this fabric is 2.6 cubic centimeters per gram. The fabric of the present invention thus has a bulk improvement of 27% as compared to the conventional fabric used as the control.

A series of similar fabrics woven from yarn containing various percentages of 20% residual shrinkage polyethylene terephthalate staple is prepared. Bulk determination made on these fabrics is plotted against percentage of high residual shrinkage staple. The resulting curve is the lower curve in the figure.

Example 111 A typical mens wear worsted, American worsted spun, is prepared in accordance with the present invention employing a fiber blend as follows:

25% of 2 /2 inch length, 4.5 denier staple produced from a polymer of acrylonitrile (95 acrylonitrile-% methyl acrylate) having a residual shrinkage of about 20% 40% of 2 /2 inch length, 2.0 denier staple produced from a polymer of acrylonitrile (95% acrylonitrile-5% methyl acrylate) having a residual shrinkage of about 3% 5% of 2 /2 inch length, 4.5 denier staple produced from a polymer of acrylonitrile (95 acrylonitrile-5% methyl acrylate) having a residual shrinkage of about 3% 15% of 2 /2 inch length, 3.0 denier commercial regenerated cellulose rayon 15 wool The yarn is spun to a 2/54 wool count having a Z twist of 15 turns per inch in the singles and 17 turns per inch in the ply. The yarn is woven in a 2 x 2 twill, 60 ends by 50 picks in the loom. The fabric in the greige is napped by 2 passes on face and back using light to medium energy. It is then fulled 1 /2 hours at room temperature employing a wool fulling solution and operating under wool fulling mill adjustments. Thereafter, tacked in rope form, it is beck scoured at the boil for 1 hour. After being cooled slowly to 140 F. to prevent rope marking, it is dried at 250 F. in a pin tenter, the tenter being overfed by and the fabric being 2 inches under width to permit relaxation. The fabric is then cropped and while relaxed, semi-decated for 5 minutes under steam and dried under vacuum for 3 minutes. A shrinkage (greige to finished) of 17% in the warp and 20% in the filling is observed. The fabric possesses high bulk and loft.

Example IV A typical mens wear flannel, woolen spun, is prepared in accordance with the present invention employing a fiber blend as follows:

50% of 2 /2 inch length, 3.0 denier staple produced from a polymer of acrylonitrile (95% acrylonitrile-5% methyl acrylate) having a residual shrinkage of about 20% 20% of 2 /2 inch length, 3.0 denier staple produced from a polymer of acrylonitrile (95% acry1onitrile-5% methyl acrylate) having a residual shrinkage of about 3% 30% of 6670s wool The yarn is spun to a weight of 7% run having a Z twist of 12 turns per inch. The yarn is woven in a 2 x 2 twill, 54 ends by 46 picks in the loom. The fabric in the greige is napped by 2 passes'on its face and l on its back with medium energy. It is then fulled /2 hour at room temperature, employing a wool fulling solution and operating under wool fulling mill adjustments. Thereafter it is dolly washed for 2 hours at 140 F. with soap and water. It is then tentered at 160 F. at its wet width and 3% 'overfeed. Following this the fabric is dyed in a closed beck employing an overhead'steam line (212 F.) under normal dyeing procedures. It is dried in a pin tenter at wet'width at 160 F., being overfed by 3%. It is napped at medium energy, several passes being made on'face"and back. After cropping it issemi-decated under mild conditions' A shrinkage of 21% (greige. to

finished) in the filling is noted. Thefabric possesses high bulk and loft.

The staple having high residual shrinkage employed in the process of the present invention may be any orientable man-made fiber. Among these may be mentioned those produced from regenerated cellulose, cellulose derivatives such as cellulose acetate, polycondensation products such as polyamides and polyesters and the polymers obtained by addition polymerization from ethylenically unsaturated low molecular compounds, for instance, acrylonitrile, vinylidene chloride, vinyl chloride and copolymers thereof. Furthermore, two or more different of such fibers may be mixed.

Residual shrinkage may be induced by various methods known to the art, such as by employing a draw ratio less than maximum and employing a lower than optimum (for shrinkage stability) temperature during drying and the like. Shrinkage can be induced by conventional physical or chemical methods after fabric manufacture. These may consist of heating by various means, as by application of water, oil, steam, air or other fluid which is relatively inert with respect to the particular filamentary material. Retraction of the material may be accomplished with a swelling agent in addition to or in place of the heat treatment. A combination of chemical and physical treatments may be used. Any method of shortening the end-to-end length of the filamentary material without too adversely affecting the fiber structure itself is acceptable. Preferably the shortening is done under the minimum practical amount of restraint. Shrinking may be accomplished along with another finishing operation, such as dyeing, drying, desizing and the like. The low residual shrinkage fiber (around 3%) component may be any commercially available man-made fiber such as a member of the class defined above or any natural fiber. Among suitable natural fibers may be mentioned cotton, flax, jute, silk, wool or the like. As demonstrated in the examples, the fabric may be manufactured from man-made fiber or from a mixture of man-made and natural fiber. The quality of worsteds and woolens, particularly tweeds, shetlands, cheviots and flannels, is particularly enhanced by the teaching of the present invention with respect to bulk, cover and surface continuity. In making flannel by the present invention, the weave pattern is partially or wholly obscured.

While a residual shrinkage of at least about 12% in the yarn component containing high residual shrinkage is recommended, yarns of much higher residual shrinkages, for instance as high as 75% may be employed. It

ent invention has been found to result in improved cover and surface continuity in the fabrics in the construction of which it is used.

As is illustrated in the examples, the fabric after weaving in a low loom construction may be subjected to various conventional finishing operations such as napping, fulling, scouring, drying, heat setting, brushing, shearing, decating and the like. By a low loom construction" is meant a fewer number of picks and ends than is normally employed in the weaving of a fabric of the same type from conventional yarn. This is necessary to allow for shrinkage of the fibers and to prevent the finished fabric from becoming over constructed. While the optimum re duction in picks and ends will vary considerably depending upon the amount of shrinkable fiber used, the amount of fiber shrinkage, and the finishing procedure used, nevertheless a reduction of at least about 5% is usually desirable. As is obvious to those skilled in the art, the yarns containing high shrinkagestaple may be spun to finer counts than normal if it is desired to compensate for increase in yarn denier resulting from shrinkage. The fabrics of the present invention have particular utility in the manufacture of apparel fabrics. However, they may be employed in many other applications such as draperies and filter cloths and for other domestic and industrial ends.

Many other equivalent modifications will be apparent to those skilled in the art from a reading of the above without a departure from the inventive concept.

What is claimed is:

A process for preparing a high bulk fabric which comprises weaving a fabric at a relatively low loom construction from a yarn formed from a mixture of at least two staple fiber components which upon heating in a relaxed state possess different shrinkage capacities, at least about 10% of the said yarn being a man-made staple fiber which has the capacity of being shrunk by a difierential at least 10% greater than the capacity of said other component staple fiber which comprises about 20% of the said yarn, and thereafter shrinking the said staple fiber having the higher shrinkage capacity by a differential at least 10% greater than the staple fiber of lower shrinkage capacity to produce a shrinkage stable fabric.

References Cited in the file of this patent UNITED STATES PATENTS 2,277,782 Rugeley Mar. 31, 1942 2,369,395 Heymann Feb. 13, 1945 2,450,948 Foster Oct. 12, 1948 2,504,523 Harris et a1. Apr. 18, 1950 2,536,163 Field et a1. Ian. 2, 1951 2,656,585 Jackson Oct. 27, 1953 2,686,339 Holt Aug. 17, 1954 2,701,406 Bloch Feb. 8, 1955 2,805,463 Laval Sept. 10, 1957 2,310,281 Appleton et a1. Oct. 22, 1957 OTHER REFERENCES Du Pont Textile Fibers Technical Information Preliminary Bulletin OR-42, December 1954, 57-140B. 

